1. Technical Field
This application relates to a vascular device and more particularly to a vascular device for approximating the vessel wall and placing a valve for treating venous valve insufficiency.
2. Background of Related Art
Veins in the body transport blood to the heart and arteries carry blood away from the heart. The veins have one-way valve structures in the form of leaflets disposed annularly along the inside wall of the vein which open to permit blood flow toward the heart and close to prevent back flow. That is, when blood flows through the vein, the pressure forces the valve leaflets apart as they flex in the direction of blood flow and move towards the inside wall of the vessel, creating an opening therebetween for blood flow. The leaflets, however, do not normally bend in the opposite direction and therefore return to a closed position to prevent blood flow in the opposite, i.e. retrograde, direction after the pressure is relieved. The leaflet structures, when functioning properly, extend radially inwardly toward one another such that the tips contact each other to block backflow of blood.
In the condition of venous valve insufficiency, the valve leaflets do not function properly as they thicken and lose flexibility, resulting in their inability to extend sufficiently radially inwardly to enable their tips to come into sufficient contact with each other to prevent retrograde blood flow. The retrograde blood flow causes the buildup of hydrostatic pressure on the residual valves and the weight of the blood dilates the wall of the vessel. Such retrograde blood flow, commonly referred to as reflux, leads to swelling and varicose veins, causing great discomfort and pain to the patient. Such retrograde blood flow, if left untreated can also cause venous stasis ulcers of the skin and subcutaneous tissue. There are generally two types of venous valve insufficiency: primary and secondary. Primary venous valve insufficiency is typically a condition from birth, where the vein is simply too large in relation to the leaflets so that the leaflets cannot come into adequate contact to prevent backflow. More common is secondary venous valve insufficiency which is caused by clots which gel and scar, thereby changing the configuration of the leaflets, i.e. thickening the leaflets creating a “stub-like” configuration. Venous valve insufficiency can occur in the superficial venous system, such as the saphenous veins in the leg, or in the deep venous system, such as the femoral and popliteal veins extending along the back of the knee to the groin.
A common method of treatment of venous valve insufficiency is placement of an elastic stocking around the patient's leg to apply external pressure to the vein, forcing the walls radially inwardly to force the leaflets into apposition. Although sometimes successful, the tight stocking is quite uncomfortable, especially in warm weather, as the stocking must be constantly worn to keep the leaflets in apposition. The elastic stocking also affects the patient's physical appearance, thereby potentially having an adverse psychological affect. This physical and/or psychological discomfort sometimes results in the patient remove the stocking, thereby preventing adequate treatment.
Another method of treatment has been developed to avoid the discomfort of the stocking. This method involves major surgery requiring the implantation of a cuff internally of the body, directly around the vein. This surgery requires a large incision, resulting in a long patient recovery time, scarring and carries the risks, e.g. anesthesia, inherent with surgery.
Another invasive method of surgery involves selective repairing of the valve leaflets, referred to as valvuloplasty. In one method, sutures are utilized to bring the free edges of the valve cusp into contact. This procedure is complicated and has the same disadvantages of the major surgery described above.
Commonly assigned U.S. Pat. Nos. 6,695,878 and 6,527,800, the entire contents of which are incorporated herein by reference as noted above, disclose an advantageous method and device to minimally invasively treat venous valve insufficiency without requiring an outer stocking or internal cuff. Such device avoids the physical and psychological discomfort of an external stocking as well as avoids the risk, complexity and expense of surgically implanted cuffs. The device is advantageously inserted minimally invasively, i.e. intravascularly, and functions to effectively bring the valve leaflets into apposition. This device first expands against the vessel wall to grasp the wall, and then contracts to bring the vessel wall radially inwardly so the leaflets can be pulled closer together to a functional position.
The vascular device of commonly assigned U.S. Pat. No. 6,676,698, the entire contents of which is incorporated by reference, utilizes the device of these foregoing applications for bringing the vessel wall radially inwardly to correct the dilation of the wall, but rather than rely on the patient's existing valve leaflets which may be scarred or non-functional, contains a replacement valve as a substitute for the patient's leaflets. Thus, advantageously, venous valve insufficiency can be treated minimally invasively by bringing the vessel wall inwardly and replacing the patient's valve.
It would be beneficial to provide additional retention structure for such devices. Additionally, it would be beneficial to minimize the insertion dimension of the device, thereby reducing the incision size to maximize the advantages of minimally invasive surgery.